Ion pair induced supramolecular assembly for development of novel pyridine 2, 6 diamide spacer acyl hydrazone-based derivatives for selective sensing of ZnCl2 and AlCl3

The work reports the development of a novel pyridine 2, 6 diamide spacer acyl hydrazone-based dual sensor H2L via two intermediates 1 and 2. The sensor as well as intermediates have been spectroscopically characterized. The structure of intermediate 1 is validated by its single crystal data analysis. As H2L bears both amide and acyl hydrazone moiety which have selective detection ability of anion and cation respectively, after rigorous characterization, the sensors are exposed to check their dual binding behavior. The results of several spectroscopic studies disclose the fact that H2L can optically and fluorometrically detect Al (III) and Zn (II) among several competitive cations and Cl− among competitive anions in semi-aqueous and aqueous medium respectively. Interestingly in a 9:1 DMSO-water medium, the probe can act as an ion pair sensor and in this medium, the probe can simultaneously detect Zn (II)/Cl- and Al (III)/Cl- forming H2L-ZnCl2, H2L-AlCl3 adduct. The 1:1 probe-analyte ion-pair binding is confirmed by NMR and mass spectral study. The Density Functional Theory (DFT) study optimizes the structures of the probe-analyte complexes. Impressively the probe has the potential to detect and quantify the Al (III) from market-available drug samples.